My crypto algorithm

crypto.php

<?
/*
 * Encrypts any number into a 10-digit cypher.
 * Oh, 10 here means 10 in a random base.
 */
class Encrypter
{
  function encrypt($num)
  {
    $str = "";
    $x = rand(1, 9);
    $str .= $x;
    for($i = 0; $i < $x; $i++) {
      $str .= rand(0, 9);
    }
    while($num != 0) {
      $y = $num % 10;
      $z = ($y + $x) % 10;
      $str .= $z;
      for($i = 0; $i < $y; $i++) {
        $str .= rand(0, 9);
      }
      $num = (int)($num / 10);
    }
    return $str;
  }

  function decrypt($text)
  {
    $i = 0;
    $m = 1;
    $n = 0;
    $x = intval($text{$i});
    $i += $x + 1;
    while($i < strlen($text)) {
      $z = $text{$i};
      $z -= $x;
      if ($z < 0) $z += 10;
      $n += $m * $z;
      $i += $z + 1;
      $m *= 10;
    }
    return $n;
  }
}

$num = 1234;

$crypter = new Encrypter();
$crypted = $crypter->encrypt($num);
$decrypted = $crypter->decrypt($crypted);

echo "Original: $num, Encrypted: $crypted, Decrypted: $decrypted\n";
?>